Analysis of Optimally Composed EV Pools for the Aggregated Provision of Frequency Containment Reserve and Energy Arbitrage Trading

Electric vehicles (EVs) can participate in various markets through a vehicle-to-grid (V2G) interface. Aggregators can combine the individual contributions of EVs to offer them, for example, on the frequency containment reserve (FCR) market or to use them for arbitrage trading. A simple approach is combining EVs in random fashion until the pool is able to reach the threshold for a service of choice. Alternatively, aggregators can compose their pools in smart fashion and include only EVs that contribute significantly to the pool's performance. In a previous publication, we have shown that optimizing the aggregated pools of commercial vehicles for the provision of FCR or arbitrage trading can increase revenues by up to 7-fold. In this work, we analyze the optimally composed pools and show that large vehicle batteries in the order of 80 kWh are particularly useful for arbitrage trading, while FCR provision is also possible with medium-sized EV batteries in the range of 30 kWh due to the small cycle depths. The inclusion of EVs with very small vehicle batteries around 20 kWh in aggregated pools is neither economically optimal for arbitrage trading nor for FCR provision. An analysis of the economic sectors of the commercial EVs selected for the optimal EV pools shows that some economic sectors are more suitable for V2G than others: In particular EVs of the sector "human health and social work activities" are unsuitable for V2G provision due to regular and long travel times during the day. In contrast, EVs from the "manufacturing" sector are particularly well represented in all applications and the "transportation and storage" sector in the arbitrage application. In addition to these analyses of the optimized pools, we reveal that a reduction in the required minimum power and increments would make the FCR market even more attractive to EV pools by increasing revenues by 50% to 66%. It would also better exploit the potential of EVs, as increments could be better utilized than they are in the current 1 MW minimum power requirement in central Europe.